The present invention concerns a technique for installing various cables and a coil to be used in this erection technique and, more particularly, a cable erection technique and a cable erection coil, simplifying the cable erection work and, at the same time, allowing to hold cables in a stable state during and after the erection work.
In general, when various cables such as communication cable or television cable or the like are to be erected, a messenger wire is put up as tensile line between utility poles, and metal hangers such as cable hangers are attached one by one to this messenger wire with an interval of 50 to 60 cm, for hanging cables in parallel.
However, in the cable erection work mentioned above, the operator carries a number of metal hangers, and attaches these hangers moving with an interval of 50 to 60 cm along the longitudinal direction of the messenger wire, and moreover, this hanger attachment operation is done in a height; therefore, such operation has been requiring tremendous time and labor, and considerably high skill.
Of late years, as a method for simplifying the cable erection work, it has been proposed to use an elastic chain coil formed into a continuous spiral from synthetic resin base material. When a cable is erected by means of chain coil, it is possible to insert the chain coil outside the messenger wire, to elongate this chain coil along the messenger wire and, at the same time, to extend the cable inside the coil and fix as it is. Therefore, the cable erection workability can be improved remarkably.
However, while the elastic chain coil presents an advantage of simple erection as mentioned above, on the contrary, when the fastener to the messenger wire is off, or when a part thereof is cut off by an accident or fire due to the component of synthetic resin, the coil shrinks causing such a problem that the cable droops. Besides, when the cable is erected by elongating the chain coil, if the coil fixed end comes off, or the elongated non fixed end is released accidentally, the chain cable shrinks to its original length by its elastic flexibility, obliging to resume the cable erection from the beginning and thus deteriorating its workability.